Method and system for managing subscription services with a cable modem

ABSTRACT

A method and system for managing network services such as subscription services from a cable modem in a data-over-cable system. The cable modem receives an initialization message on a cable television connection indicating what services are available on a data network. The cable modem uses a connection to a public switched telephone network in the data-over-cable system to send requests to and receive responses from the data network. A telephony remote access concentrator on the public switched telephone network provides an additional security mechanism by not allowing a cable modem to subscribe to unauthorized services. Using the public switched telephone network does not compromise the security of the cable television network. In addition, the public switched telephone network is used to provide administrative support to the cable television network on lower bandwidth connections by providing an administrative pathway outside of the higher bandwidth cable television connections.

FIELD OF INVENTION

The present invention relates to communications in computer networks.More specifically, it relates to a method and system for managingsubscription services with a cable modem with telephony return.

BACKGROUND OF THE INVENTION

Cable television networks such as those provided by Comcast CableCommunications, Inc., of Philadelphia, Pa., Cox Communications ofAtlanta Ga., Tele-Communications, Inc., of Englewood Colo., Time-WarnerCable, of Marietta Ga., Continental Cablevision, Inc., of Boston Mass.,and others provide cable television services to a large number ofsubscribers over a large geographical area. The cable televisionnetworks typically are interconnected by cables such as coaxial cablesor a Hybrid Fiber/Coaxial ("HFC") cable system which have data rates ofabout 10 Mega-bits-per-second ("Mbps") to 30+ Mbps.

The Internet, a world-wide-network of interconnected computers, providesmultimedia content including audio, video, graphics and text thatrequires a large bandwidth for downloading and viewing. Most InternetService Providers ("ISPs") allow customers to connect to the Internetvia a serial telephone line from a Public Switched Telephone Network("PSTN") at data rates including 14,400 bps, 28,800 bps, 33,600 bps,56,000 bps and others that are much slower than the about 10 Mbps to 30+Mbps available on a coxial cable or HFC cable system on a cabletelevision network.

With the explosive growth of the Internet, many customers have desiredto use the larger bandwidth of a cable television network to connect tothe Internet and other computer networks. Cable modems, such as thoseprovided by 3Com Corporation of Santa Clara, Calif., U.S. RoboticsCorporation of Skokie, Ill., and others offer customers higher-speedconnectivity to the Internet, an intranet, Local Area Networks ("LANs")and other computer networks via cable television networks. These cablemodems currently support a data connection to the Internet and othercomputer networks via a cable television network with a "downstream"data rate of 30+ Mbps, which is a much larger data rate than can besupported by serial telephone line used over a modem.

However, most cable television networks provide only uni-directionalcable systems, supporting only a "downstream" data path. A downstreamdata path is the flow of data from a cable system "headend" to acustomer. A cable system headend is a central location in the cabletelevision network that is responsible for sending cable signals in thedownstream direction. A return data path via a telephone network, suchas a Public Switched Telephone Network provided by AT&T and others,(i.e., "telephony return") is typically used for an "upstream" datapath. An upstream data path is the flow of data from the customer backto the cable system headend. A cable television system with an upstreamconnection to a telephony network is called a "data-over-cable systemwith telephony return."

An exemplary data-over-cable system with telephony return includes acable modem termination system, a cable television network, a publicswitched telephone network, a telephony remote access concentrator, acable modem, customer premise equipment (e.g., a customer computer) anda data network (e.g., the Internet). The cable modem termination systemand the telephony remote access concentrator together are called a"telephony return termination system."

The cable modem termination system receives data packets from the datanetwork and transmits them downstream via the cable television networkto a cable modem attached to the customer premise equipment. Thecustomer premise equipment sends responses data packets to the cablemodem, which sends response data packets upstream via the publicswitched telephone network to the telephony remote access concentrator,which sends the response data packets back to the appropriate host onthe data network. The data-over-cable system with telephony returnprovides transparent Internet Protocol ("IP") data traffic betweencustomer premise equipment, a cable modem and the data network (e.g.,the Internet or an intranet). As is known in the art, IP is a routingprotocol designed to route traffic within a network or between networks.

When a cable modem used in the data-over-cable system with telephonyreturn is initialized, it will make a connection to both the cable modemtermination system via the cable network and to the telephony remoteaccess concentrator via the public switched telephone network. If thecable modem is using telephony return, it will acquire telephonyconnection parameters on a downstream connection from the cable modemtermination system and establish a Point-to-Point Protocol ("PPP")connection to connect an upstream channel to the telephony remote accessconcentrator. As is known in the art, PPP is used to encapsulatedatagrams over a serial communications link. After a PPP connection isestablished, the cable modem negotiates a telephony IP address with thetelephony remote access concentrator. The telephony IP address allowsthe customer premise equipment to send IP data packets upstream to thetelephony remote access concentrator via the public switched telephonenetwork to the data network. The cable modem also makes an IP connectionto the cable modem termination system so that IP data received on thecable modem termination system from the data network can be forwardeddownstream to the customer premise equipment via the cable network andthe cable modem.

A cable modem in a data-over-cable system can be used to allow a user tosubscribe to one or more services offered by a data network. Forexample, the cable modem can be used to subscribe a user to a particularInternet Service Provider ("ISP"), or connect to a specific Internet orintranet site, or access a desired Internet Service.

However, there are several problems with using a cable modem in adata-over-cable system to subscribe to services or connect to sitesoffered by a data network. Security of the cable television network orthe cable modem termination system can be compromised by allowing a userwith a cable modem to subscribe to one or more services on the datanetwork without security checks. For example, a user may subscribe to aservice on the data network that is undesirable or incompatible for usewith the cable modem termination system or cable network. The servicemay use a protocol that is incompatible with the cable televisionnetwork subscribe or provide content that may be undesirable based onpolicies established by the cable television network. The providers ofthe cable television network may also desire to limit cable modem usersto specific services and not allow cable modem users to subscribe to allavailable services on a data network unless additional fees are paid. Inaddition, the higher bandwidth downstream cable television connectionsare used for administrative tasks when a lower bandwidth telephonyconnection via a public switched telephone network is available in thedata over-cable system with telephony return. It is desirable to use thetelephony return path to allow a cable modem to subscribe to services ona data network outside of cable television connections.

SUMMARY OF THE INVENTION

In accordance with an illustrative embodiment of the present invention,the problems associated with using a cable modem in a data-over-cablesystem to subscribe to services offered by a data network are overcome.A method and system is provided for management of services for a datanetwork from a network device. The method includes a data-over-cablesystem with a network device connected to a first network with adownstream connection of a first connection type, connected to a secondnetwork with an upstream connection of a second connection type andconnected to the second network with a second downstream connection ofthe second connection type. The first and second networks are connectedto a third network with a third connection type. In an illustrativeembodiment of the present invention, the network device is a cablemodem, the first network is a cable television network, the secondnetwork is a public switched telephone network and the third network isa data network (e.g., the Internet or an intranet). The first connectiontype is a cable television connection, the second connection type is atelephony connection and the third connection type is an InternetProtocol connection. However, other network devices, networks andconnection types can also be used and the present invention is notlimited to these network devices, networks or connections.

The method includes receiving a first message from the first network onthe first downstream connection on the network device, wherein the firstmessage includes a list of services on the third network available tothe network device. The list of services from the first message isstored on the network device.

A second message is sent from the network device on the upstreamconnection to the second network, wherein the second message includes arequest for one or more of the network services available on the thirdnetwork. A third message is received on the second downstream connectionfrom the second network on the network device. The third messageindicates a status for of the one or more available network servicesrequested by the network device in the second message.

The method allows a cable modem to subscribe to one or more networkservices available on the data network without comprising the securityof the cable television network or the cable modem termination system. Atelephony remote access concentrator also uses the list of servicesavailable to the cable modem on the data network to provide anadditional security mechanism. The telephony remote access concentratorreceives the list of services in a management message from a cable modemtermination system. The first and management messages contain apre-determined list of services available on the data network such as alist of Internet or intranet sites available to the cable modem. In anillustrative embodiment of the present invention, the predetermined listis small set of Internet or intranet sites on the data network the cablemodem is allowed to connect to.

Thus, the cable modem has access only to the small set of Internet orintranet sites on the data network provided in the first message anddoes not have access to all sites and service available on the datanetwork. The telephony remote access concentrator checks the list ofservices each time a cable modem requests a service on the data network.If the cable modem requests a service that is not in the list ofservices maintained by the telephony remote access concentrator, therequest for services by the cable modem is rejected. In anotherembodiment of the present invention, the small set of Internet orintranet sites are preferred sites only and the cable modem has accessto all sites and services available on the data network and thetelephony remote access concentrator will not reject requests from thecable modem.

An illustrative embodiment of the present invention allows a cable modemto request one or more services available on a data network such as theInternet or an intranet by using a telephony return pathway in thedata-over-cable system. Using the telephony return path improves thesecurity of the cable television system. In addition, the telephonyreturn path is used to provide administrative support on lower bandwidthconnections for a data-over-cable system by providing an administrativepathway outside of the higher bandwidth cable television connections.

The foregoing and other features and advantages of an illustrativeembodiment of the present invention will be more readily apparent fromthe following detailed description, which proceeds with references tothe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a cable modem system withtelephony return;

FIG. 2 is a block diagram illustrating a protocol stack for a cablemodem;

FIG. 3 is a block diagram illustrating a Telephony Channel Descriptormessage structure;

FIG. 4 is a block diagram illustrating a Termination System Informationmessage structure;

FIG. 5 is a flow diagram illustrating a method for addressing hosts in acable modem system;

FIG. 6 is a block diagram illustrating a Dynamic Host ConfigurationProtocol message structure;

FIGS. 7A and 7B are a flow diagram illustrating a method for discoveringhosts in a cable modem system;

FIG. 8 is a block diagram illustrating a data-over-cable system for themethod illustrated in FIGS. 7A and 7B;

FIG. 9 is a block diagram illustrating the message flow of the methodillustrated in FIGS. 7A and 7B;

FIGS. 10A and 10B are a flow diagram illustrating a method for resolvinghost addresses in a data-over-cable system;

FIGS. 11A and 11B are a flow diagram illustrating a method for resolvingdiscovered host addresses; and

FIG. 12 is a block diagram illustrating the message flow of the methodillustrated in FIG. 10;

FIGS. 13A and 13B arc a flow diagram illustrating a method for obtainingaddresses for customer premise equipment;

FIGS. 14A and 14B are a flow diagram illustrating a method for resolvingaddresses for customer premise equipment;

FIGS. 15A and 15B are a flow diagram illustrating a method foraddressing network host interfaces from customer premise equipment;

FIGS. 16A and 16B are a flow diagram illustrating a method for resolvingnetwork host interfaces from customer premise equipment;

FIG. 17 is a block diagram illustrating a message flow for the methodsin FIGS. 15A, 15B, and 16A and 16B;

FIG. 18 is a flow diagram illustrating a cable modem system withtelephony return;

FIG. 19 is a flow diagram illustrating a method for managing networkservices from a network device; and

FIG. 20 is a flow diagram illustrating a method for managing networkservices from a cable modem;

FIG. 21 is a flow diagram illustrating a method for managing networkservices from a network; and

FIG. 22 is a flow diagram illustrating a method for managing networkservices from a telephony remote termination system.

DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT

Cable modem system with telephony return

FIG. 1 is a block diagram illustrating a data-over-cable system withtelephony return 10, hereinafter data-over-cable system 10. Most cableproviders known in the art predominately provide uni-directional cablesystems, supporting only a "downstream" data path. A downstream datapath is the flow of data from a cable television network "headend" tocustomer premise equipment (e.g., a customer's personal computer). Acable television network headend is a central location that isresponsible for sending cable signals in a downstream direction. Areturn path via a telephony network ("telephony return") is typicallyused for an "upstream" data path in uni-directional cable systems. Anupstream data path is the flow of data from customer premise equipmentback to the cable television network headend.

However, data-over-cable system 10 of the present invention may alsoprovide a bi-directional data path (i.e., both downstream and upstream)without telephony return as is also illustrated in FIG. 1 and thepresent invention is not limited to a data-over-cable system withtelephony return. In a data-over cable system without telephony return,customer premise equipment or cable modem has an upstream connection tothe cable modem termination system via a cable television connection, awireless connection, a satellite connection, or a connection via othertechnologies to send data upstream to the cable modem terminationsystem.

Data-over-cable system 10 includes a Cable Modem Termination System("CMTS") 12 connected to a cable television network 14, hereinaftercable network 14. Cable network 14 includes cable television networkssuch as those provided by Comcast Cable Communications, Inc., ofPhiladelphia, Pa., Cox Communications, or Atlanta, Ga.,Tele-Communications, Inc., of Englewood Colo., Time-Warner Cable, ofMarietta, Ga., Continental Cablevision, Inc., of Boston, Mass., andothers. Cable network 14 is connected to a Cable Modem ("CM") 16 with adownstream cable connection.

CM 16 is connected to Customer Premise Equipment ("CPE") 18 such as apersonal computer system via a Cable Modem-to-CPE Interface ("CMCI") 20.CM 16 is connected to a Public Switched Telephone Network ("PSTN") 22with an upstream telephony connection. PSTN 22 includes those publicswitched telephone networks provided by AT&T, Regional Bell OperatingCompanies (e.g., Ameritch, U.S. West, Bell Atlantic, Southern BellCommunications, Bell South, NYNEX, and Pacific Telesis Group), GTE, andothers. The upstream telephony connection is any of a standard telephoneline connection, Integrated Services Digital Network ("ISDN")connection, Asymmetric Digital Subscriber Line ("ADSL") connection, orother telephony connection. PSTN 22 is connected to a Telephony RemoteAccess Concentrator ("TRAC") 24. In a data-over cable system withouttelephony return, CM 16 has an upstream connection to CMTS 12 via acable television connection, a wireless connection, a satelliteconnection, or a connection via other technologies to send data upstreamoutside of the telephony return path. An upstream cable televisionconnection via cable network 14 is illustrated in FIG. 1.

FIG. 1 illustrates a telephony modem integral to CM 16. In anotherembodiment of the present invention, the telephony modem is a separatemodem unit external to CM 16 used specifically for connecting with PSTN22. A separate telephony modem includes a connection to CM 16 forexchanging data. CM 16 includes cable modems provided by the 3ComCorporation of Santa Clara, Calif., U.S. Robotics Corporation of Skokie,Ill., and others. In yet another embodiment of the present invention, CM16 includes functionality to connect only to cable network 14 andreceives downstream signals from cable network 14 and sends upstreamsignals to cable network 14 without telephony return. The presentinvention is not limited to cable modems used with telephony return.

CMTS 12 and TRAC 24 may be at a "headend" of cable system 10, or TRAC 24may be located elsewhere and have routing associations to CMTS 12. CMTS12 and TRAC 24 together are called a "Telephony Return TerminationSystem" ("TRTS") 26. TRTS 26 is illustrated by a dashed box in FIG. 1.CMTS 12 and TRAC 24 make up TRTS 26 whether or not they are located atthe headend of cable network 14, and TRAC 24 may in located in adifferent geographic location from CMTS 12. Content severs, operationsservers, administrative servers and maintenance servers used indata-over-cable system 10 (not shown in FIG. 1) may also be in differentlocations. Access points to data-over-cable system 10 are connected toone or more CMTS's 12 or cable headend access points. Suchconfigurations may be "one-to-one", "one-to-many," or "many-to-many,"and may be interconnected to other Local Area Networks ("LANs") or WideArea Networks ("WANs").

TRAC 24 is connected to a data network 28 (e.g., the Internet or anintranet) by a TRAC-Network System Interface 30 ("TRAC-NSI"). CMTS 12 isconnected to data network 28 by a CMTS-Network System Interface("CMTS-NSI") 32. The present invention is not limited to data-over-cablesystem 10 illustrated in FIG. 1, and more or fewer components,connections and interfaces could also be used.

Cable modem protocol stack

FIG. 2 is a block diagram illustrating a protocol stack 36 for CM 16.FIG. 2 illustrates the downstream and upstream protocols used in CM 16.As is known in the art, the Open System Interconnection ("OSI") model isused to describe computer networks. The OSI model consists of sevenlayers including from lowest-to-highest, a physical, data-link, network,transport, session, application and presentation layer. The physicallayer transmits bits over a communication link. The data link layertransmits error free frames of data. The network layer transmits androutes data packets.

For downstream data transmission, CM 16 is connected to cable network 14in a physical layer 38 via a Radio Frequency ("RF") Interface 40. In anillustrative embodiment of the present invention, RF Interface 40 has anoperation frequency range of 50 Mega-Hertz ("MHz") to 1 Giga-Hertz("GHz") and a channel bandwidth of 6 MHz. However, other operationfrequencies may also be used and the invention is not limited to thesefrequencies. RF interface 40 uses a signal modulation method ofQuadrature Amplitude Modulation ("QAM"). As is known in the art, QAM isused as a means of encoding digital information over radio, wire, orfiber optic transmission links. QAM is a combination of amplitude andphase modulation and is an extension of multiphase phase-shift-keying.QAM can have any number of discrete digital levels typically including4, 16, 64 or 256 levels. In one embodiment of the present invention,QAM-64 is used in RF interface 40. However, other operating frequenciesmodulation methods could also be used. For more information on RFinterface 40 see the Institute of Electrical and Electronic Engineers("IEEE") standard 802.14 for cable modems incorporated herein byreference. IEEE standards can be found on the World Wide Web at theUniversal Resource Locator ("LURL") "www.ieee.org." However, other RFinterfaces 40 could also be used and the present invention is notlimited to IEEE 802.14 (e.g., RF interfaces from Multimedia CableNetwork Systems ("MCNS") and other could also be used).

Above RF interface 40 in a data-link layer 42 is a Medium Access Control("MAC") layer 44. As is known in the art, MAC layer 44 controls accessto a transmission medium via physical layer 38. For more information onMAC layer protocol 44 see IEEE 802.14 for cable modems. However, otherMAC layer protocols 44 could also be used and the present invention isnot limited to IEEE 802.14 MAC layer protocols (e.g., MCNS MAC layerprotocols and others could also be used).

Above MAC layer 44 is an optional link security protocol stack 46. Linksecurity protocol stack 46 prevents authorized users from making a dataconnection from cable network 14. RF interface 40 and MAC layer 44 canalso be used for an upstream connection if data-over-cable system 10 isused without telephony return.

For upstream data transmission with telephony return, CM 16 is connectedto PSTN 22 in physical layer 38 via modem interface 48. TheInternational Telecommunications Union-Telecommunication StandardizationSector ("ITU-T", formerly known as the CCITT) defines standards forcommunication devices identified by "V.xx" series where "xx" is anidentifying number. ITU-T standards can be found on the World Wide Webat the URL "www.itu.ch."

In one embodiment of the present invention, ITU-T V.34 is used as modeminterface 48. As is known in the art, ITU-T V.34 is commonly used in thedata link layer for modem communications and currently allows data ratesas high as 33,600 bits-per-second ("bps"). For more information see theITU-T V.34 standard. However, other modem interfaces or other telephonyinterfaces could also be used.

Above modem interface 48 in data link layer 42 is Point-to-PointProtocol ("PPP") layer 50, hereinafter PPP 50. As is known in the art,PPP is used to encapsulate network layer datagrams over a serialcommunications link. For more information on PPP see InternetEngineering Task Force ("IETF") Request for Comments ("RFC"), RFC-1661,RFC-1662 and RFC-1663 incorporated herein by reference. Information forIETF RFCs can be found on the World Wide Web at URLs "ds.internic.net"or "www.ietf.org."

Above both the downstream and upstream protocol layers in a networklayer 52 is an Internet Protocol ("IP") layer 54. IP layer 54,hereinafter IP 54, roughly corresponds to OSI layer 3, the networklayer, but is typically not defined as part of the OSI model. As isknown in the art, IP 54 is a routing protocol designed to route trafficwithin a network or between networks. For more information on IP 54 seeRFC-791 incorporated herein by reference.

Internet Control Message Protocol ("ICMP") layer 56 is used for networkmanagement. The main functions of ICMP layer 56, hereinafter ICMP 56,include error reporting, reachability testing (e.g., "pinging")congestion control, route-change notification, performance, subnetaddressing and others. Since IP 54 is an unacknowledged protocol,datagrams may be discarded and ICMP 56 is used for error reporting. Formore information on ICMP 56 see RFC-971 incorporated herein byreference.

Above IP 54 and ICMP 56 is a transport layer 58 with User DatagramProtocol layer 60 ("UDP"). UDP layer 60, hereinafter UDP 60, roughlycorresponds to OSI layer 4, the transport layer, but is typically notdefined as part of the OSI model. As is known in the art, UDP 60provides a connectionless mode of communications with datagrams. Formore information on UDP 60 see RFC-768 incorporated herein by reference.

Above the network layer are a Simple Network Management Protocol("SNMP") layer 62, Trivial File Protocol ("TFTP") layer 64, Dynamic HostConfiguration Protocol ("DHCP") layer 66 and a UDP manager 68. SNMPlayer 62 is used to support network management functions. For moreinformation on SNMP layer 62 see RFC-1157 incorporated herein byreference. TFTP layer 64 is a file transfer protocol used to downloadfiles and configuration information. For more information on TFTP layer64 see RFC-1350 incorporated herein by reference. DHCP layer 66 is aprotocol for passing configuration information to hosts on an IP 54network. For more information on DHCP layer 66 see RFC-1541 incorporatedherein by reference. UDP manager 68 distinguishes and routes packets toan appropriate service (e.g., a virtual tunnel). More or few protocollayers could also be used with data-over-cable system 10.

CM 16 supports transmission and reception of IP 54 datagrams asspecified by RFC-791. CMTS 12 and TRAC 24 may perform filtering of IP 54datagrams. CM 16 is configurable for IP 54 datagram filtering torestrict CM 16 and CPE 18 to the use of only their assigned IP 54addresses. CM 16 is configurable for IP 54 datagram UDP 60 portfiltering (i.e., deep filtering).

CM 16 forwards IP 54 datagrams destined to an IP 54 unicast addressacross cable network 14 or PSTN 22. Some routers have security featuresintended to filter out invalid users who alter or masquerade packets asif sent from a valid user. Since routing policy is under the control ofnetwork operators, such filtering is a vendor specific implementation.For example, dedicated interfaces (i.e., Frame Relay) may exist betweenTRAC 24 and CMTS 12 which preclude filtering, or various forms ofvirtual tunneling and reverse virtual tunneling could be used tovirtually source upstream packets from CM 16. For more information onvirtual tunneling see Level 2 Tunneling Protocol ("L2TP") orPoint-to-Point Tunneling Protocol ("PPTP") in IETF draft documentsincorporated herein by reference by Kory Hamzeh, et. al (IETF draftdocuments are precursors to IETF RFCs and are works in progress).

CM 16 also forwards IP 54 datagrams destined to an IP 54 multicastaddress across cable network 14 or PSTN 22. CM 16 is configurable tokeep IP 54 multicast routing tables and to use group membershipprotocols. CM 16 is also capable of IP 54 tunneling upstream through thetelephony path. A CM 16 that wants to send a multicast packet across avirtual tunnel will prepend another IP 54 header, set the destinationaddress in the new header to be the unicast address of CMTS 12 at theother end of the tunnel, and set the IP 54 protocol field to be four,which means the next protocol is IP 54.

CMTS 12 at the other end of the virtual tunnel receives the packet,strips off the encapsulating IP 54 header, and forwards the packet asappropriate. A broadcast IP 54 capability is dependent upon theconfiguration of the direct linkage, if any, between TRAC 24 and CMTS12. CMTS 12, CM 16, and TRAC 24 are capable of routing IP 54 datagramsdestined to an IP 54 broadcast address which is across cable network 14or PSTN 22 if so configured. CM 16 is configurable for IP 54 broadcastdatagram filtering.

An operating environment for CM 16 of the present invention includes aprocessing system with at least one high speed Central Processing Unit("CPU") and a memory system. In accordance with the practices of personsskilled in the art of computer programming, the present invention isdescribed below with reference to acts and symbolic representations ofoperations that are performed by the processing system, unless indicatedotherwise. Such acts and operations are sometimes referred to as being"computer-executed", or "CPU executed."

It will be appreciated that the acts and symbolically representedoperations include the manipulation of electrical signals by the CPU.The electrical system represent data bits which cause a resultingtransformation or reduction of the electrical signal representation, andthe maintenance of data bits at memory locations in the memory system tothereby reconfigure or otherwise alter the CPU's operation, as well asother processing of signals. The memory locations where data bits aremaintained are physical locations that have particular electrical,magnetic, optical, or organic properties corresponding to the data bits.

The data bits may also be maintained on a computer readable mediumincluding magnetic disks, optical disks, organic disks, and any othervolatile or non-volatile mass storage system readable by the CPU. Thecomputer readable medium includes cooperating or interconnected computerreadable media, which exist exclusively on the processing system or isdistributed among multiple interconnected processing systems that may belocal or remote to the processing system.

Initialization of a cable modem with telephony return

When CM 16 is initially powered on, if telephony return is being used,CM 16 will receive a Telephony Channel Descriptor ("TCD") from CMTS 12that is used to provide dialing and access instructions on downstreamchannels via cable network 14. Information in the TCD is used by CM 16to connect to TRAC 24. The TCD is transmitted as a MAC managementmessage with a management type value of TRI₋₋ TCD at a periodic interval(e.g., every 2 seconds). To provide for flexibility, the TCD messageparameters are encoded in a Type/Length/Value ("TLV") form. However,other encoding techniques could also be used.

FIG. 3 is a block diagram illustrating a TCD message structure 70 withMAC 44 management header 72 and Service Provider Descriptor(s) ("SPD")74 encoded in TLV format. SPDs 74 are compound TLV encodings that definetelephony physical-layer characteristics that are used by CM 16 toinitiate a telephone call. SPD 74 is a TLV-encoded data structure thatcontains sets of dialing and access parameters for CM 16 with telephonyreturn. SPD 74 is contained within TCD message 70. There may be multipleSPD 74 encodings within a single TCD message 70. There is at least oneSPD 74 in TCD message 70. SPD 74 parameters are encoded as SPD-TLVtuples. SPD 74 contains the parameters shown in Table 1 and may containoptional vendor specific parameters. However, more or fewer parameterscould also be used in SPD 74.

                  TABLE 1                                                         ______________________________________                                        SPD 74 Parameter                                                                            Description                                                     ______________________________________                                        Factory Default Flag                                                                        Boolean value, if TRUE(1), indicates a                                        SPD which should be used by CM 16.                              Service Provider Name                                                                       This parameter includes the name of a                                         service provider. Format is standard                                          ASCII string composed of numbers and                                          letters.                                                        Telephone Numbers                                                                           These parameters contain telephone                                            numbers that CM 16 uses to initiate a                                         telephony modem link during a login                                           process. Connections are attempted in                                         ascending numeric order (i.e., Phone                                          Number 1, Phone Number 2...). The SPD                                         contains a vaild telephony dial string as                                     the primary dial string (Phone Number 1),                                     secondary dial-strings are optional.                                          Format is ASCII string(s) composed of:                                        any sequence of numbers, pound "#" and                                        star "*" keys and comma character ","                                         used to indicate a two second pause in                                        dialing.                                                        Connection Threshold                                                                        The number of sequential connection                                           failures before indicating connection                                         failure. A dial attempt that does not result                                  in an answer and connection after no                                          more than ten rings is considered a                                           failure. The default value is one.                              Login User Name                                                                             This contains a user name CM 16 will use                                      an authentication protocol over the                                           telephone link during the initialization                                      procedure. Format is a monolithic                                             sequence of alphanumeric characters in                                        an ASCII string composed of numbers                                           and letters.                                                    Login Password                                                                              This contains a password that CM 16 will                                      use during authentication over a                                              telephone link during the initialization                                      procedure. Format is a monolithic                                             sequence of alphanumeric characters in                                        an ASCII string composed of numbers                                           and letters.                                                    DHCP Authenticate                                                                           Boolean value, reserved to indicate that                                      CM 16 uses a specific indicated DHCP 66                                       Server (see next parameter) for a DHCP                                        66 Client and BOOTP Relay Process                                             when TRUE (one). The default is FALSE                                         (zero) which allows any DHCP 66 Server.                         DHCP Server   IP 54 address value of a DHCP 66 Server                                       CM 16 uses for DHCP 66 Client and                                             BOOTP Relay Process. If this attribute is                                     present and DHCP 66 Authenticate                                              attribute is TRUE(1). The default value is                                    integer zero.                                                   RADIUS Realm  The realm name is a string that defines a                                     RADIUS server domain. Format is a                                             monolithic sequence of alphanumeric                                           characters in an ACSII string composed                                        of numbers and letters.                                         PPP Authentication                                                                          This parameter instructs the telephone                                        modem which authentication procedure to                                       perform over the telephone link.                                Demand Dial Timer                                                                           This parameter indicates time (in                                             seconds) of inactive networking time that                                     will be allowed to elapse before hanging                                      up a telephone connection at CM 16. If                                        this optional parameter is not present, or                                    set to zero, then the demand dial feature                                     is not activated. The default value is zero.                    Vendor Specific Extensions                                                                  Optional vendor specific extensions.                            ______________________________________                                    

A Termination System Information ("TSI") message is transmitted by CMTS12 at periodic intervals (e.g., every 2 seconds) to report CMTS 12information to CM 16 whether or not telephony return is used. The TSImessage is transmitted as a MAC 44 management message. The TSI providesa CMTS 12 boot record in a downstream channel to CM 16 via cable network14. Information in the TSI is used by CM 16 to obtain information aboutthe status of CMTS 12. The TSI message has a MAC 44 management typevalue of TRI₋₋ TSI.

FIG. 4 is a block diagram of a TSI message structure 76. TSI messagestructure 76 includes a MAC 44 management header 78, a downstreamchannel IP address 80, a registration IP address 82, a CMTS 12 boot time84, a downstream channel identifier 86, an epoch time 88 and vendorspecific TLV encoded data 90.

A description of the fields of TSI message 76 are shown in Table 2.However, more or fewer fields could also be used in TSI message 76.

                  TABLE 2                                                         ______________________________________                                        TSI 76 Parameter                                                                              Description                                                   ______________________________________                                        Downstream Channel                                                                            This field contains an IP 54 address of                       IP Address 80   CMTS 12 available on the downstream                                           channel this message arrived on.                              Registration IP Address 82                                                                    This field contains an IP 54 address                                          CM 16 sends its registration request                                          messages to. This address MAY be                                              the same as the Downstream Channel                                            IP 54 address.                                                CMTS Boot Time 84                                                                             Specifies an absolute-time of a CMTS                                          12 recorded epoch. The clock setting                                          for this epoch uses the current clock                                         time with an unspecified accuracy.                                            Time is represented as a 32 bit binary                                        number.                                                       Downstream Channel ID 86                                                                      A downstream channel on which this                                            message has been transmitted. This                                            identifier is arbitrarily chosen by CMTS                                      12 and is unique within the MAC 44                                            layer.                                                        Epoch 88        An integer value that is incremented                                          each time CMTS 12 is either re-                                               initialized or performs address or                                            routing table flush.                                          Vendor Specific Extensions 90                                                                 Optional vendor extensions may be                                             added as TLV encoded data.                                    ______________________________________                                    

After receiving TCD 70 message and TSI message 76, CM 16 continues toestablish access to data network 28 (and resources on the network) byfirst dialing into TRAC 24 and establishing a telephony PPP 50 session.Upon the completion of a successful PPP 50 connection, CM 16 performsPPP Link Control Protocol ("LCP") negotiation with TRAC 24. Once LCPnegotiation is complete, CM 16 requests Internet Protocol ControlProtocol ("IPCP") address negotiation. For more information on IPCP seeRFC-1332 incorporated herein by reference. During IPCP negotiation, CM16 negotiates an IP 54 address with TRAC 24 for sending IP 54 datapacket responses back to data network 28 via TRAC 24.

When CM 16 has established an IP 54 link to TRAC 24, it begins"upstream" communications to CMTS 12 via DHCP layer 66 to complete avirtual data connection by attempting to discover network hostinterfaces available on CMTS 12 (e.g., IP 54 host interfaces for avirtual IP 54 connection). The virtual data connection allows CM 16 toreceive data from data network 28 via CMTS 12 and cable network 14, andsend return data to data network 28 via TRAC 24 and PSTN 22. CM 16 mustfirst determine an address of a host interface (e.g., an IP 54interface) available on CMTS 12 that can be used by data network 28 tosend data to CM 16. However, CM 16 has only a downstream connection fromCMTS 12 and has to obtain a connection address to data network 28 usingan upstream connection to TRAC 24.

Addressing network host interfaces in the data-over-cable system via thecable modem

FIG. 5 is a flow diagram illustrating a method 92 for addressing networkhost interfaces in a data-over-cable system with telephony return via acable modem. Method 92 allows a cable modem to establish a virtual dataconnection to a data network. In method 92, multiple network devices areconnected to a first network with a downstream connection of a firstconnection type, and connected to a second network with an upstreamconnection of a second connection type. The first and second networksare connected to a third network with a third connection type.

At step 94, a selection input is received on a first network device fromthe first network over the downstream connection. The selection inputincludes a first connection address allowing the first network device tocommunicate with the first network via upstream connection to the secondnetwork. At step 96, a first message of a first type for a firstprotocol is created on the first network device having the firstconnection address from the selection input in a first message field.The first message is used to request a network host interface address onthe first network. The first connection address allows the first networkdevice to have the first message with the first message type forwardedto network host interfaces available on the first network via theupstream connection to the second network.

At step 98, the first network device sends the first message over theupstream connection to the second network. The second network uses thefirst address field in the first message to forward the first message toone or more network host interfaces available on first network at step100. Network host interfaces available on the first network that canprovide the services requested in first message send a second messagewith a second message type with a second connection address in a secondmessage field to the first network at step 102. The second connectionaddress allows the first network device to receive data packets from thethird network via a network host interface available on the firstnetwork. The first network forwards one or more second messages on thedownstream connection to the first network device at step 104.

The first network device selects a second connection address from one ofthe second messages from one of the one or more network host interfacesavailable on the first network at step 106 and establishes a virtualconnection from the third network to the first network device using thesecond connection address for the selected network host interface.

The virtual connection includes receiving data on the first network hostinterface on the first network from the third network and sending thedata over the downstream connection to the first network device. Thefirst network device sends data responses back to the third network overthe upstream connection to the second network, which forwards the datato the appropriate destination on the third network.

In one embodiment of the present invention, the data-over-cable systemis data-over-cable system 10, the first network device is CM 16, thefirst network is cable television network 14, the downstream connectionis a cable television connection. The second network is PSTN 22, theupstream connection is a telephony connection, the third network is datanetwork 28 (e.g., the Internet or an intranet) and the third type ofconnection is an IP 54 connection. The first and second connectionaddresses are IP 54 addresses. However, the present invention is notlimited to the network components and addresses described. Method 92allows CM 16 to determine an IP 54 network host interface addressavailable on CMTS 12 to receive IP 54 data packets from data network 28,thereby establishing a virtual IP 54 connection with data network 28.

After addressing network host interfaces using method 92, an exemplarydata path through cable system 10 is illustrated in Table 3. Howeverother data paths could also be used and the present invention is notlimited to the data paths shown in Table 3. For example, CM 16 may senddata upstream back through cable network 14 (e.g., CM 16 to cablenetwork 14 to CMTS 12) and not use PSTN 22 and the telephony returnupstream path.

                  TABLE 3                                                         ______________________________________                                        1.  An IP 54 datagram from data network 28 destined for CM 16                     arrives on CMTS-NSI 32 and enters CMTS 12.                                2.  CMTS 12 encodes the IP 54 datagram in a cable data frame, passes it           it to MAC 44 and transmits it "downstream" to RF interface                    40 on CM 16 via cable network 14.                                         3.  CM 16 recognizes the encoded IP 54 datagram in MAC layer 44                   received via RF interface 40.                                             4.  CM 16 responds to the cable data frame and encapsulates a response            IP 54 datagram in a PPP 50 frame and transmits it "upstream" with             modem interface 48 via PSTN 22 to TRAC 24.                                5.  TRAC 24 decodes the IP 54 datagram and forwards it via                        TRAC-NSI 30 to a destination on data network 28.                          ______________________________________                                    

Dynamic network host configuration on data-over-cable system

As was illustrated in FIG. 2, CM 16 includes a Dynamic HostConfiguration Protocol ("DHCP") layer 66, hereinafter DHCP 66. DHCP 66is used to provide configuration parameters to hosts on a network (e.g.,an IP 54 network). DHCP 66 consists of two components: a protocol fordelivering host-specific configuration parameters from a DHCP 66 serverto a host and a mechanism for allocation of network host addresses tohosts. DHCP 66 is built on a client-server model, where designated DHCP66 servers allocate network host addresses and deliver configurationparameters to dynamically configured network host clients.

FIG. 6 is a block diagram illustrating a DHCP 66 message structure 108.The format of DHCP 66 messages is based on the format of BOOTstrapProtocol ("BOOTP") messages described in RFC-951 and RFC-1542incorporated herein by reference. From a network host client's point ofview, DHCP 66 is an extension of the BOOTP mechanism. This behaviorallows existing BOOTP clients to interoperate with DHCP 66 serverswithout requiring any change to network host the clients' BOOTPinitialization software. DHCP 66 provides persistent storage of networkparameters for network host clients.

To capture BOOTP relay agent behavior described as part of the BOOTPspecification and to allow interoperability of existing BOOTP clientswith DHCP 66 servers, DHCP 66 uses a BOOTP message format. Using BOOTPrelaying agents eliminates the necessity of having a DHCP 66 server oneach physical network segment.

DHCP 66 message structure 108 includes an operation code field 110("op"), a hardware address type field 112 ("htype"), a hardware addresslength field 114 ("hlen"), a number of hops field 116 ("hops"), atransaction identifier field 118 ("xid"), a seconds elapsed time field120 ("secs"), a flags field 122 ("flags"), a client IP address field 124("ciaddr"), a your IP address field 126 ("yiaddr"), a server IP addressfield 128 ("siaddr"), a gateway/relay agent IP address field 130("giaddr"), a client hardware address field 132 ("chaddr"), an optionalserver name field 134 ("sname"), a boot file name 136 ("file") and anoptional parameters field 138 ("options"). Descriptions for DHCP 66message 108 fields are shown in Table 4.

                  TABLE 4                                                         ______________________________________                                        DCHP 66                                                                       Parameter    Description                                                      ______________________________________                                        OP 110       Message op code/message type.                                                 1 BOOTREQUEST, 2 = BOOTREPLY.                                    HTYPE 112    Hardware address type (e.g., `1` = 10                                         Mps Ethernet).                                                   HLEN 114     Hardware address length (e.g. `6` for 10                                      Mbps Ethernet).                                                  HOPS 116     Client sets to zero, optionally used by                                       relay-agents when booting via a relay-                                        agent.                                                           XID 118      Transaction ID, a random number                                               chosen by the client, used by the client                                      and server to associate messages and                                          responses between a client and a                                              server.                                                          SECS 120     Filled in by client, seconds elapsed                                          since client started trying to boot.                             FLAGS 122    Flags including a BROADCAST bit.                                 CIADDR 124   Client IP address; filled in by client in                                     DHCPREQUEST if verifying previously                                           allocated configuration parameters.                              YIADDR 126   `Your`(client) IP address.                                       SIADDR 128   IP 54 address of next server to use in                                        bootstrap; returned in DHCPOFFER,                                             DHCPACK and DHCPNAK by server.                                   GIADDR 130   Gateway relay agent IP 54 address,                                            used in booting via a relay-agent.                               CHADDR       Client hardware address (e.g., MAC                               132          layer 44 address).                                               SNAME 134    Optional server host name, null                                               terminated string.                                               FILE 136     Boot file name, terminated by a null                                          string.                                                          OPTIONS      Optional parameters.                                             138                                                                           ______________________________________                                    

The DHCP 66 message structure shown in FIG. 6 is used to discover IP 54and other network host interfaces in data-over-cable system 10. Anetwork host client (e.g., CM 16) uses DHCP 66 to acquire or verify anIP 54 address and network parameters whenever the network parameters mayhave changed. Table 5 illustrates a typical use of the DHCP 66 protocolto discover a network host interface from a network host client.

                  TABLE 5                                                         ______________________________________                                        1.  A network host client broadcasts a DHCP 66 discover message on                its local physical subnet. The DHCP 66 discover message may                   include options that suggest values for a network host interface              address. BOOTP relay agents may pass the message on to DHCP 66                servers not on the same physical subnet.                                  2.  DHCP servers may respond with a DHCPOFFER message that                        includes an available network address in the `yiaddr` field (and              other configuration parameters in DHCP 66 options) from a network             host interface. DHCP 66 servers unicasts the DHCPOFFER message                to the network host client (using the DHCP/BOOTP relay agent                  if necessary) if possible, or may broadcast the message to a                  broadcast address (preferably 255.255.255.255) on the client's                subnet.                                                                   3.  The network host client receives one or more DHCPOFFER                        messages from one or more DHCP 66 servers. The network host                   client may choose to wait for multiple responses.                         4.  The network host client chooses one DHCP 66 server with an                    associated network host interface from which to request                       configuration parameters, based on the configuration                          parameters offered in the DHCPOFFER messages.                             ______________________________________                                    

Discovering network host interfaces in the data-over-cable system

The DHCP discovery process illustrated in table 5 will not work indata-over-cable system 10. CM 16 has only a downstream connection fromCMTS 12, which includes DHCP 66 servers, associated with network hostinterfaces available on CMTS 12. In an illustrative embodiment of thepresent invention, CM 16 discovers network host interfaces via TRAC 24and PSTN 22 on an upstream connection.

The DHCP 66 addressing process shown in Table 5 was not originallyintended to discover network host interfaces in data-over-cable system10. CMTS 12 has DHCP 66 servers associated with network host interfaces(e.g., IP interfaces), but CM 16 only has as downstream connection fromCMTS 12. CM 16 has an upstream connection to TRAC 24, which has a DHCP66 layer. However, TRAC 24 does not have DHCP 66 servers, or directaccess to network host interfaces on CMTS 12.

FIGS. 7A and 7B are a flow diagram illustrating a method 140 fordiscovering network host interfaces in data-over-cable system 10. WhenCM 16 has established an IP 54 link to TRAC 24, it begins communicationswith CMTS 12 via DHCP 66 to complete a virtual IP 54 connection withdata network 28. However, to discover what IP 54 host interfaces mightbe available on CMTS 12, CM 16 has to communicate with CMTS 12 via PSTN22 and TRAC 24 since CM 16 only has a "downstream" cable channel fromCMTS 12.

At step 142 in FIG. 7A, after receiving a TSI message 76 from CMTS 12 ona downstream connection, CM 16 generates a DHCP discover("DHCPDISCOVER") message and sends it upstream via PSTN 22 to TRAC 22 todiscover what IP 54 interfaces are available on CMTS 12. The fields ofthe DHCP discover message are set as illustrated in Table 6. However,other field settings may also be used.

                  TABLE 6                                                         ______________________________________                                        DHCP 66                                                                       Parameter   Description                                                       ______________________________________                                        OP 110      Set to BOOTREQUEST.                                               HTYPE 112   Set to network type (e.g., one for 10 Mbps                                    Ethernet).                                                        HLEN 114    Set to network length (e.g., six for 10 Mbps                                  Ethernet)                                                         HOPS 116    Set to zero.                                                      FLAGS 118   Set BROADCAST bit to zero.                                        CIADDR 124  If CM 16 has previously been assigned an IP                                   54 address, the IP 54 address is placed in this                               field. If CM 16 has previously been assigned                                  an IP 54 address by DHCP 66, and also has                                     been assigned an address via IPCP, CM 16                                      places the DHCP 66 IP 54 address in this                                      field.                                                            GIADDR 130  CM 16 places the Downstream Channel IP 54                                     address 80 of CMTS 12 obtained in TSI                                         message 76 on a cable downstream channel                                      in this field.                                                    CHADDR 132  CM 16 places its 48-bit MAC 44 LAN address                                    in this field.                                                    ______________________________________                                    

The DHCPDISCOVER message is used to "discover" the existence of one ormore IP 54 host interfaces available on CMTS 12. DHCP 66 giaddr-field130 (FIG. 6) includes the downstream channel IP address 80 of CMTS 12obtained in TSI message 76 (e.g., the first message field from step 96of method 92). Using the downstream channel IP address 80 of CMTS 12obtained in TSI message 76 allows the DHCPDISCOVER message to beforwarded by TRAC 24 to DHCP 66 servers (i.e., protocol servers)associated with network host interfaces available on CMTS 12. If DHCP 66giaddr-field 130 (FIG. 6) in a DHCP message from a DHCP 66 client isnon-zero, the DHCP 66 server sends any return messages to a DHCP 66server port on a DHCP 66 relaying agent (e.g., CMTS 12) whose addressappears in DHCP 66 giaddr-field 130.

In a typical DHCP 66 discovery process the DHCP 66 giaddr-field 130 isset to zero. If DHCP 66 giaddr-field 130 is zero, the DHCP 66 client ison the same subnet as the DHCP 66 server, and the DHCP 66 server sendsany return messages to either the DHCP 66 client's network address, ifthat address was supplied in DHCP 66 ciaddr-field 124 (FIG. 6), or to aclient's hardware address specified in DHCP 66 chaddr-field 132 (FIG. 6)or to a local subnet broadcast address (e.g., 255.255.255.255).

At step 144, a DHCP 66 layer on TRAC 24 broadcasts the DHCPDISCOVERmessage on its local network leaving DHCP 66 giaddr-field 130 intactsince it already contains a non-zero value. TRAC's 24 local networkincludes connections to one or more DHCP 66 proxies (i.e., network hostinterface proxies). The DHCP 66 proxies accept DHCP 66 messagesoriginally from CM 16 destined for DHCP 66 servers connected to networkhost interfaces available on CMTS 12 since TRAC 24 has no direct accessto DCHP 66 servers associated with network host interfaces available onCMTS 12. DHCP 66 proxies are not used in a typical DHCP 66 discoveryprocess.

One or more DHCP 66 proxies on TRAC's 24 local network recognizes theDHCPDISCOVER message and forwards it to one or more DHCP 66 serversassociated with network host interfaces (e.g., IP 54 interfaces)available on CMTS 12 at step 146. Since DHCP 66 giaddr-field 130 (FIG.6) in the DHCPDISCOVER message sent by CM 16 is already non-zero (i.e.,contains the downstream IP address of CMTS 12), the DHCP 66 proxies alsoleave DHCP 66 giaddr-field 130 intact.

One or more DHCP 66 servers for network host interfaces (e.g., IP 54interfaces) available on CMTS 12 receive the DHCPDISCOVER message andgenerate a DHCP 66 offer message ("DHCPOFFER") at step 148. The DHCP 66offer message is an offer of configuration parameters sent from networkhost interfaces to DHCP 66 servers and back to a network host client(e.g., CM 16) in response to a DHCPDISCOVER message. The DHCP 66 offermessage is sent with the message fields set as illustrated in Table 7.However, other field settings can also be used. DHCP 66 yiaddr-field 126(e.g., second message field from step 102 of method 92) contains an IP54 address for a network host interface available on CMTS 12 and usedfor receiving data packets from data network 28.

                  TABLE 7                                                         ______________________________________                                        DHCP 66 Parameter                                                                             Description                                                   ______________________________________                                        FLAGS 122       BROADCAST bit set to zero.                                    YIADDR 126      IP 54 address from a network                                                  host interface to allow CM 16 to                                              receive data from data network                                                28 via a network host interface                                               available on CMTS 12.                                         SIADDR 128      An IP 54 address for a TFTP 64                                                server to download configuration                                              information for an interface host.                            CHADDR 132      MAC 44 address of CM 16.                                      SNAME 134       Optional DHCP 66 server                                                       identifier with an interface host.                            FILE 136        A TFTP 64 configuration file                                                  name for CM 16.                                               ______________________________________                                    

DHCP 66 servers send the DHCPOFFER message to the address specified in66 giaddr-field 130 (i.e., CMTS 12) from the DHCPDISCOVER message ifassociated network host interfaces (e.g., IP 54 interfaces) can offerthe requested service (e.g., IP 54 service) to CM 16. The DHCPDISOVERmessage DHCP 66 giaddr-field 130 contains a downstream channel IPaddress 80 of CMTS 12 that was received by CM 16 in TSI message 76. Thisallows CMTS 12 to receive the DHCPOFFER messages from the DHCP 66servers and send them to CM 16 via a downstream channel on cable network14.

At step 150 in FIG. 7B, CMTS 12 receives one or more DHCPOFFER messagesfrom one or more DHCP 66 servers associated with the network hostinterfaces (e.g., IP 54 interfaces). CMTS 12 examines DHCP 66yiaddr-field 126 and DHCP 66 chaddr-field 132 in the DHCPOFFER messagesand sends the DHCPOFFER messages to CM 16 via cable network 14. DHCP 66yiaddr-field 126 contains an IP 54 address for a network host IP 54interface available on CMTS 12 and used for receiving IP 54 data packetsfrom data network 28. DHCP 66 chaddr-field 132 contains the MAC 44 layeraddress for CM 16 on a downstream cable channel from CMTS 12 via cablenetwork 14. CMTS 12 knows the location of CM 16 since it sent CM 16 aMAC 44 layer address in one or more initialization messages (e.g., TSImessage 76).

If a BROADCAST bit in flags field 124 is set to one, CMTS 12 sends theDHCPOFFER messages to a broadcast IP 54 address (e.g., 255.255.255.255)instead of the address specified in DHCP 66 yiaddr-field 126. DHCP 66chaddr-field 132 is still used to determine that MAC 44 layer address.If the BROADCAST bit in DHCP 66 flags field 122 is set, CMTS 12 does notupdate internal address or routing tables based upon DHCP 66yiaddr-field 126 and DHCP 66 chaddr-field 132 pair when a broadcastmessage is sent.

At step 152, CM 16 receives one or more DHCPOFFER messages from CMTS 12via cable network 14 on a downstream connection. At step 154, CM 16selects an offer for IP 54 service from one of the network hostinterfaces (e.g., an IP interfaces 54) available on CMTS 12 thatresponded to the DHCPDISOVER message sent at step 142 in FIG. 7A andestablishes a virtual IP 54 connection. The selected DHCPOFFER messagecontains a network host interface address (e.g., IP 54 address) in DHCP66 yiaddr-field 126 (FIG. 6). A cable modem acknowledges the selectednetwork host interface with DHCP 66 message sequence explained below.

After selecting and acknowledging a network host interface, CM 16 hasdiscovered an IP 54 interface address available on CMTS 12 forcompleting a virtual IP 54 connection with data network 28.Acknowledging a network host interface is explained below. The virtualIP 54 connection allows IP 54 data from data network 28 to be sent toCMTS 12 which forwards the IP 54 packets to CM 16 on a downstreamchannel via cable network 14. CM 16 sends response IP 54 packets back todata network 28 via PSTN 22 and TRAC 24.

FIG. 8 is a block diagram illustrating a data-over-cable system 156 forthe method illustrated in FIGS. 7A and 7B. Data-over-cable system 156includes DHCP 66 proxies 158, DHCP 66 servers 160 and associated NetworkHost Interfaces 162 available on CMTS 12. Multiple DHCP 66 proxies 158,DHCP 66 servers 160 and network host interfaces 162 are illustrated assingle boxes in FIG. 8. FIG. 8 also illustrates DHCP 66 proxies 158separate from TRAC 24. In one embodiment of the present invention, TRAC24 includes DHCP 66 proxy functionality and no separate DHCP 66 proxies158 are used. In such an embodiment, TRAC 24 forwards DHCP 66 messagesusing DHCP 66 giaddr-field 130 to DHCP 66 servers 160 available on CMTS12. FIG. 9 is a block diagram illustrating a message flow 162 of method140 (FIGS. 7A and 7B).

Message flow 162 includes DHCP proxies 158 and DHCP servers 160illustrated in FIG. 8 Steps 142, 144, 146, 148, 150 and 154 of method140 (FIGS. 7A and 7B) are illustrated in FIG. 9. In one embodiment ofthe present invention, DHCP proxies 158 are not separate entities, butare included in TRAC 24. In such an embodiment, DHCP proxy services areprovided directly by TRAC 24.

Resolving addresses for network host interfaces

Since CM 16 receives multiple DHCPOFFER messages (Step 152 FIG. 7B) CM16 resolves and acknowledges one offer from a selected network hostinterface. FIGS. 10A and 10B are a flow diagram illustrating a method166 for resolving and acknowledging host addresses in a data-over-cablesystem. Method 166 includes a first network device that is connected toa first network with a downstream connection of a first connection type,and connected to a second network with an upstream connection of asecond connection type. The first and second networks are connected to athird network with a third connection type. In one embodiment of thepresent invention, the first network device is CM 16, the first networkis cable network 14, the second network is PSTN 22 and the third networkis data network 28 (e.g., the Internet). The downstream connection is acable television connection, the upstream connection is a telephonyconnection, and the third connection is an IP connection.

Turning to FIG. 10A, one or more first messages are received on thefirst network device from the first network on the downstream connectionat step 168. The one or more first messages are offers from one or morenetwork host interfaces available on the first network to provide thefirst network device a connection to the third network. The firstnetwork device selects one of the network host interfaces using messagefields in one of the one or more first messages at step 170. The firstnetwork device creates a second message with a second message type toaccept the offered services from a selected network host interface atstep 172. The second message includes a connection address for the firstnetwork in a first message field and an identifier to identify theselected network host interface in a second message field.

The first network device sends the second message over the upstreamconnection to the second network at step 174. The second network usesthe first message field in the second message to forward the secondmessage to the one or more network host interfaces available on firstnetwork at step 176.

A network host interface available on the first network identified insecond message field in the second message from the first network devicerecognizes an identifier for the network host interface at 178 in FIG.10B. The selected network host interface sends a third message with athird message type to the first network at step 180. The third messageis an acknowledgment for the first network device that the selectednetwork host interface received the second message from the firstnetwork device. The first network stores a connection address for theselected network interface in one or more tables on the first network atstep 182. The first network will forward data from the third network tothe first network device when it is received on the selected networkhost interface using the connection address in the one or more routingtables. The first network forwards the third message to the firstnetwork device on the downstream connection at step 184. The firstnetwork device receives the third message at step 186. The first networkand the first network device have the necessary addresses for a virtualconnection that allows data to be sent from the third network to anetwork host interface on the first network, and from the first networkover the downstream connection to the first network device. Method 166accomplishes resolving network interface hosts addresses from a cablemodem in a data-over-cable with telephony return.

Method 166 of the present invention is used in data-over-cable system 10with telephony return. However, the present invention is not limited todata-over-cable system 10 with telephony return and can be used indata-over-cable system 10 without telephony return by using an upstreamcable channel instead of an upstream telephony channel.

FIGS. 11A and 11B are a flow diagram illustrating a method 188 forresolving discovered host addresses in data-over-cable system 10 withtelephony return. At step 190 in FIG. 11A, CM 16 receives one or moreDHCPOFFER messages from one or more DHCP 66 servers associated with oneor more network host interfaces (e.g., at step 168 in method 166). Theone or more DHCPOFFER messages include DHCP 66 fields set as illustratedin Table 7 above. However, other field settings could also be used. Atstep 192, CM 16 selects one of the DHCPOFFER messages (see also, step170 in method 166). At step 194, CM 16 creates a DHCP 66 request message("DHCPREQUEST") message to request the services offered by a networkhost interface selected at step 192. The fields of the DHCP requestmessage are set as illustrated in Table 8. However, other field settingsmay also be used.

                  TABLE 8                                                         ______________________________________                                        DHCP 66                                                                       Parameter   Description                                                       ______________________________________                                        OP 110      Set to BOOTREQUEST.                                               HTYPE 112   Set to network type (e.g. one for 10 Mbps                                     Ethernet).                                                        HLEN 114    Set to network length (e.g., six for 10 Mbps                                  Ethernet)                                                         HOPS 116    Set to zero.                                                      FLAGS 118   Set BROADCAST bit to zero.                                        CIADDR 124  If CM 16 has previously been assigned an IP                                   address, the IP address is placed in this field.                              If CM 16 has previously been assigned an IP                                   address by DHCP 66, and also has been                                         assigned an address via IPCP, CM 16 places                                    the DHCP 66 IP 54 address in this field.                          YIADDR 126  IP 54 address sent from the selected network                                  interface host in DCHPOFFER message                               GIADDR 130  CM 16 places the Downstream Channel IP 54                                     address 80 CMTS 12 obtained in TSI                                            message 76 on a cable downstream channel                                      in this field.                                                    CHADDR 132  CM 16 places its 48-bit MAC 44 LAN address                                    in this field.                                                    SNAME 134   DHCP 66 server identifier for the selected                                    network interface host                                            ______________________________________                                    

The DHCPREQUEST message is used to "request" services from the selectedIP 54 host interface available on CMTS 12 using a DHCP 66 serverassociated with the selected network host interface. DHCP 66giaddr-field 130 (FIG. 6) includes the downstream channel IP address 80for CMTS 12 obtained in TSI message 76 (e.g., the first message-fieldfrom step 172 of method 166). Putting the downstream channel IP address80 obtained in TSI message 76 allows the DHCPREQUEST message to beforwarded by TRAC 24 to DCHP 66 servers associated with network hostinterfaces available on CMTS 12. DHCP 66 giaddr-field 126 contains anidentifier (second message field, step 172 in method 166) DHCP 66sname-field 134 contains a DHCP 66 server identifier associated with theselected network host interface.

If DHCP 66 giaddr-field 130 in a DHCP message from a DHCP 66 client isnon-zero, a DHCP 66 server sends any return messages to a DHCP 66 serverport on a DHCP 66 relaying agent (e.g., CMTS 12) whose address appearsin DHCP 66 giaddr-field 130. If DHCP 66 giaddr-field 130 is zero, theDHCP 66 client is on the same subnet as the DHCP 66 server, and the DHCP66 server sends any return messages to either the DHCP 66 client'snetwork address, if that address was supplied in DHCP 66 ciaddr-field124, or to the client's hardware address specified in DHCP 66chaddr-field 132 or to the local subnet broadcast address.

Returning to FIG. 11A at step 196, CM 16 sends the DHCPREQUEST messageon the upstream connection to TRAC 24 via PSTN 22. At step 198, a DHCP66 layer on TRAC 24 broadcasts the DHCPREQUEST message on its localnetwork leaving DHCP 66 giaddr-field 130 intact since it alreadycontains a non-zero value. TRAC's 24 local network includes connectionsto one or more DHCP 66 proxies. The DHCP 66 proxies accept DHCP 66messages originally from CM 16 destined for DHCP 66 servers associatedwith network host interfaces available on CMTS 12. In another embodimentof the present invention, TRAC 24 provides the DHCP 66 proxyfunctionality, and no separate DHCP 66 proxies are used.

The one or more DHCP 66 proxies on TRAC's 24 local network messageforwards the DHCPOFFER to one or more of the DHCP 66 servers associatedwith network host interfaces (e.g., IP 54 interfaces) available on CMTS12 at step 200 in FIG. 11B. Since DHCP 66 giaddr-field 130 in theDHCPDISCOVER message sent by CM 16 is already non-zero (i.e., containsthe downstream IP address of CMTS 12), the DHCP 66 proxies leave DHCP 66giaddr-field 130 intact.

One or more DHCP 66 servers for the selected network host interfaces(e.g., IP 54 interface) available on CMTS 12 receives the DHCPOFFERmessage at step 202. A selected DHCP 66 server recognizes a DHCP 66server identifier in DHCP 66 sname-field 134 or the IP 54 address thatwas sent in the DCHPOFFER message in the DHCP 66 yiaddr-field 126 fromthe DHCPREQUST message as being for the selected DHCP 66 server.

The selected DHCP 66 server associated with network host interfaceselected by CM 16 in the DHCPREQUEST message creates and sends a DCHP 66acknowledgment message ("DHCPACK") to CMTS 12 at step 204. The DHCPACKmessage is sent with the message fields set as illustrated in Table 9.However, other field settings can also be used. DHCP 66 yiaddr-fieldagain contains the IP 54 address for the selected network host interfaceavailable on CMTS 12 for receiving data packets from data network 28.

                  TABLE 9                                                         ______________________________________                                        DHCP 66 Parameter                                                                             Description                                                   ______________________________________                                        FLAGS 122       Set a BROADCAST bit to zero.                                  YIADDR 126      IP 54 address for the selected                                                network host interface to allow                                               CM 16 to receive data from data                                               network 28.                                                   SIADDR 128      An IP 54 address for a TFTP 64                                                server to download configuration                                              information for an interface host.                            CHADDR 132      MAC 44 address of CM 16.                                      SNAME 134       DHCP 66 server identifier                                                     associated with the selected                                                  network host interface.                                       FILE 136        A configuration file name for an                                              network interface host.                                       ______________________________________                                    

The selected DHCP 66 server sends the DHCACK message to the addressspecified in DHCP 66 giaddr-field 130 from the DHCPREQUEST message to CM16 to verify the selected network host interface (e.g., IP 54 interface)will offer the requested service (e.g., IP 54 service).

At step 206, CMTS 12 receives the DHCPACK message from the selected DHCP66 server associated with the selected network host interface IP 54address(e.g., IP 54 interface). CMTS 12 examines DHCP 66 yiaddr-field126 and DHCP 66 chaddr-field 132 in the DHCPOFFER messages. DHCP 66yiaddr-field 126 contains an IP 54 address for a network host IP 54interface available on CMTS 12 and used for receiving IP 54 data packetsfrom data network 28 for CM 16. DHCP 66 chaddr-field 132 contains theMAC 44 layer address for CM 16 on a downstream cable channel from CMTS12 via cable network 14.

CMTS 12 updates an Address Resolution Protocol ("ARP") table and otherrouting tables on CMTS 12 to reflect the addresses in DHCP 66yiaddr-field 126 and DHCP 66 chaddr-field 132 at step 208. As is knownin the art, ARP allows a gateway such as CMTS 12 to forward anydatagrams from a data network such as data network 28 it receives forhosts such as CM 16. ARP is defined in RFC-826, incorporated herein byreference.

CMTS 12 stores a pair of network address values in the ARP table, the IP54 address of the selected network host interface from DHCP 66yiaddr-field 126 and a Network Point of Attachment ("NPA") address. Inan illustrative embodiment of the present invention, The NPA address isa MAC 44 layer address for CM 16 via a downstream cable channel. TheIP/NPA address pair are stored in local routing tables with the IP/NPAaddresses of hosts (e.g., CMs 16) that are attached to cable network 14.

At step 210, CMTS 12 sends the DHCPACK message to CM 16 via cablenetwork 14. At step 212, CM 16 receives the DHCPACK message, and alongwith CMTS 12 has addresses for a virtual connection between data network28 and CM 16. When data packets arrive on the IP 54 address for theselected host interface they are sent to CMTS 12 and CMTS 12 forwardsthem using a NPA (i.e., MAC 44 address) from the routing tables on adownstream channel via cable network 14 to CM 16.

If a BROADCAST bit in flags field 124 is set to one in the DHCPACK, CMTS12 sends the DHCPACK messages to a broadcast IP 54 address (e.g.,255.255.255.255). DHCP 66 chaddr-field 132 is still used to determinethat MAC layer address. If the BROADCAST bit in flags field 122 is set,CMTS 12 does not update the ARP table or offer routing tables based uponDHCP 66 yiaddr-field 126 and DHCP 66 chaddr-field 132 pair when abroadcast message is sent.

FIG. 12 is a block diagram illustrating the message flow 214 of themethod 188 illustrated in FIGS. 11A and 11B. Message flow 214 includesDHCP proxies 158 and DHCP servers 160 illustrated in FIG. 8. Methodsteps 194, 196, 198, 204, 208, 210 and 212 of method 188 (FIGS. 11A and11B) are illustrated in FIG. 12. In one embodiment of the presentinvention, DHCP proxies 158 are not separate entities, but are includedin TRAC 24. In such an embodiment, DHCP proxy services are provideddirectly by TRAC 24.

After method 188, CMTS 12 has a valid IP/MAC address pair in one or moreaddress routing tables including an ARP table to forward IP 54 datapackets from data network 28 to CM 16, thereby creating a virtual IP 54data path to/from CM 16 as was illustrated in method 92 (FIG. 5) andTable 3. CM 16 has necessary parameters to proceed to the next phase ofinitialization, a download of a configuration file via TFTP 64. Once CM16 has received the configuration file and has been initialized, itregisters with CMTS 12 and is ready to receive data from data network14.

In the event that CM 16 is not compatible with the configuration of thenetwork host interface received in the DHCPACK message, CM 16 maygenerate a DHCP 66 decline message ("DHCPDECLINE") and transmit it toTRAC 24 via PSTN 22. A DHCP 66 layer in TRAC 24 forwards the DHCPDECLINEmessage to CMTS 12. Upon seeing a DHCPDECLINE message, CMTS 12 flushesits ARP tables and routing tables to remove the now invalid IP/MACpairing. If an IP 54 address for a network host interface is returnedthat is different from the IP 54 address sent by CM 16 in theDCHCPREQUEST message, CM 16 uses the IP 54 address it receives in theDHCPACK message as the IP 54 address of the selected network hostinterface for receiving data from data network 28.

The present invention is described with respect to, but is not limitedto a data-over-cable-system with telephony return. Method 188 can alsobe used with a cable modem that has a two-way connection (i.e., upstreamand downstream) to cable network 14 and CMTS 12. In adata-over-cable-system without telephony return, CM 16 would broadcastthe DHCPREQUEST message to one or more DHCP 66 servers associated withone or more network host interfaces available on CMTS 12 using anupstream connection on data network 14 including the IP 54 address ofCMTS 12 in DHCP 66 giaddr-field 130. Method 188 accomplishes resolvingaddresses for network interface hosts from a cable modem in adata-over-cable with or without telephony return, and without extensionsto the existing DHCP protocol.

CPE initialization in a data-over-cable system

CPE 18 also uses DHCP 66 to generate requests to obtain IP 54 addressesto allow CPE 18 to also receive data from data network 28 via CM 16. Inan illustrative embodiment of the present invention, CM 16 functions asa standard BOOTP relay agent/DHCP Proxy 158 to facilitate CPE's 18access to DHCP 66 server 160. FIGS. 13A and 13B are a flow diagramillustrating a method 216 for obtaining addresses for customer premiseequipment. CM 16 and CMTS 12 use information from method 214 toconstruct IP 54 routing and ARP table entries for network hostinterfaces 162 providing data to CMCI 20 and to CPE 18.

Method 216 in FIGS. 13A and 13B includes a data-over-cable system withtelephony return and first network device with a second network devicefor connecting the first network device to a first network with adownstream connection of a first connection type, and for connecting toa second network with an upstream connection of a second connectiontype. The first and second networks are connected to a third networkwith a third connection type.

In one embodiment of the present invention, data-over-cable system withtelephony return is data-over-cable system 10 with the first networkdevice CPE 18 and the second network device CM 16. The first network iscable television network 14, the downstream connection is a cabletelevision connection, the second network is PSTN 22, the upstreamconnection is a telephony connection, the third network is data network28 (e.g., the Internet or an intranet) and the third type of connectionis an IP 54 connection. However, the present invention is not limited tothe network components described and other network components may alsobe used. Method 216 allows CPE 18 to determine an IP 54 network hostinterface address available on CMTS 12 to receive IP 54 data packetsfrom data network 54, thereby establishing a virtual IP 54 connectionwith data network 28 via CM 16.

Returning to FIG. 13A at step 218, a first message of a first type(e.g., a DHCP 66 discover message) with a first message field for afirst connection is created on the first network device. The firstmessage is used to discover a network host interface address on thefirst network to allow a virtual connection to the third network.

At step 220, the first network device sends the first message to thesecond network device. The second network device checks the firstmessage field at step 222. If the first message field is zero, thesecond network device puts its own connection address into the firstmessage field at step 224. The second network device connection addressallows the messages from network host interfaces on the first network toreturn messages to the second network device attached to the firstnetwork device. If the first message field is non-zero, the secondnetwork device does not alter the first message field since there couldbe a relay agent attached to the first network device that may set thefirst connection address field.

At step 226, the second network device forwards the first message to aconnection address over the upstream connection to the second network.In one embodiment of the present invention, the connection address is anIP broadcast address (e.g., 255.255.255.255). However, other connectionaddresses can also be used.

The second network uses the first connection address in the firstmessage field in the first message to forward the first message to oneor more network host interfaces (e.g., IP 54 network host interfaces)available on first network at step 228. One or more network hostinterfaces available on the first network that can provide the servicesrequested in first message send a second message with a second messagetype with a second connection address in a second message field to thefirst network at step 230 in FIG. 13B. The second connection addressallows the first network device to receive data packets from the thirdnetwork via a network host interface on the first network. The firstnetwork forwards the one or more second messages on the downstreamconnection to the second network device at step 232. The second networkdevice forwards the one or more second messages to the first networkdevice at step 234. The first network device selects one of the one ormore network host interfaces on the first network using the one or moresecond messages at step 236. This allows a virtual connection to beestablished between the third network and the first network device viathe selected network host interface on the first network and the secondnetwork device.

FIGS. 14A and 14B are a flow diagram illustrating a method 240 forresolving addresses for the network host interface selected by a firstnetwork device to create a virtual connection to the third network.Turning to FIG. 14A, at step 240 one or more second messages arereceived with a second message type on the first network device from thesecond network device from the first network on a downstream connectionat step 242. The one or more second messages are offers from one or moreprotocol servers associated with one or more network host interfacesavailable on the first network to provide the first network device aconnection to the third network. The first network device selects one ofthe network host interfaces using one of the one or more second messagesat step 244. The first network device creates a third message with athird message type to accept the offered services from the selectednetwork host interface at step 246. The third message includes aconnection address for the first network in a first message field and anidentifier to identify the selected network host interface in a secondmessage field. At step 248, first network device equipment sends thethird message to the second network device.

The second network device sends the third message over the upstreamconnection to the second network at step 250. The second network usesthe first message field in the third message to forward the thirdmessage to the one or more network host interfaces available on firstnetwork at step 252.

A network host interface available on the first network identified insecond message field in the third message from the first network devicerecognizes an identifier for the selected network host interface at step254 in FIG. 14B. The selected network host interface sends a fourthmessage with a fourth message type to the first network at step 256. Thefourth message is an acknowledgment for the first network device thatthe selected network host interface received the third message. Thefourth message includes a second connection address in a third messagefield. The second connection address is a connection address for theselected network host interface. The first network stores the connectionaddress for the selected network interface from the third message in oneor more routing tables (e.g., an ARP table) on the first network at step258. The first network will forward data from the third network to thefirst network device via the second network device when it is receivedon the selected network host interface using the connection address fromthe third message field. The first network forwards the fourth messageto the second network device on the downstream connection at step 260.The second network device receives the fourth message and stores theconnection address from the third message field for the selected networkinterface in one or more routing tables on the second network device atstep 262. The connection address for the selected network interfaceallows the second network device to forward data from the third networksent by the selected network interface to the customer premiseequipment.

At step 264, the second network device forward the fourth message to thefirst network device. At step 266, the first network device establishesa virtual connection between the third network and the first networkdevice.

After step 266, the first network, the second network device and thefirst network device have the necessary connection addresses for avirtual connection that allows data to be sent from the third network toa network host interface on the first network, and from the firstnetwork over the downstream connection to the second network and then tothe first network device. In one embodiment of the present invention,method 240 accomplishes resolving network interface hosts addresses fromcustomer premise equipment with a cable modem in a data-over-cable withtelephony return without extensions to the existing DHCP protocol.

Methods 216 and 240 of the present invention are used in data-over-cablesystem with telephony return with CM 16 and CPE 18. However, the presentinvention is not limited to data-over-cable system 10 with telephonyreturn and can be used in data-over-cable system 10 without telephonyreturn by using an upstream cable channel instead of an upstreamtelephony channel.

FIGS. 15A and 15B are a flow diagram illustrating a method 268 foraddressing network host interfaces from CPE 18. At step 270 in FIG. 15A,CPE 18 generates a DHCPDISCOVER message broadcasts the DHCPDISCOVERmessage on its local network with the fields set as illustrated in Table6 above with addresses for CPE 18 instead of CM 16. However, more orfewer field could also be set. CM 16 receives the DHCPDISCOVER as astandard BOOTP relay agent at step 272. The DHCP DISCOVER message has aMAC 44 layer address for CPE 18 in DHCP 66 chaddr-field 132, which CM 16stores in one or more routing tables. As a BOOTP relay agent, the CM 16checks the DHCP 66 giaddr-field 130 (FIG. 6) at step 274. If DHCP 66giaddr-field 130 is set to zero, CM 16 put its IP 54 address into DHCP66 giaddr-field 130 at step 276.

If DHCP 66 giaddr-field 130 is non-zero, CM 16 does not alter DHCP 66giaddr-field 130 since there could be another BOOTP relay agent attachedto CPE 18 which may have already set DHCP 66 giaddr-field 130. Any BOOTPrelay agent attached to CPE 18 would have also have acquired its IP 54address from using a DCHP 66 discovery process (e.g., FIG. 12).

Returning to FIG. 15A, at step 278, CM 16 broadcasts the DHCPDISCOVERmessage to a broadcast address via PSTN 22 to TRAC 24. In one embodimentof the present invention, the broadcast address is an IP 54 broadcastaddress (e.g., 255.255.255.255). At step 280, one or more DHCP 66proxies 158 associated with TRAC 24, recognize the DHCPDISOVER message,and forward it to one or more DHCP 66 servers 160 associated with one ormore network host interfaces 162 available on CMTS 12. Since DHCP 66giaddr-field 130 is already non-zero, the DHCP proxies leave DHCP 66giaddr-field 130 intact. In another embodiment of the present invention,TRAC 24 includes DCHP 66 proxy 158 functionality and no separate DHCP 66proxies 158 are used.

At step 282 in FIG. 15B, the one or more DHCP servers 160 receive theDHCPDISCOVER message from one or more DHCP proxies, and generate one ormore DHCPOFFER messages to offer connection services for one or morenetwork host interfaces 162 available on CMTS 12 with the fields set asillustrated in Table 7. The one or more DHCP servers 160 send the one ormore DHCPOFFER messages to the address specified in DHCP 66 giaddr-field130 (e.g., CM 16 or a BOOTP relay agent on CPE 18), which is an IP 54address already contained in an ARP or other routing table in CMTS 12.Since CMTS 12 also functions as a relay agent for the one or more DHCPservers 160, the one or more DHCPOFFER messages are received on CMTS 12at step 284.

CMTS 12 examines DHCP 66 yiaddr-field 126 and DHCP 66 giaddr-field 130in the DHCPOFFER messages, and sends the DHCPOFFER messages down cablenetwork 14 to IP 54 address specified in the giaddr-field 130. The MAC44 address for CM 16 is obtained through a look-up of the hardwareaddress associated with DHCP 66 chaddr-field 130. If the BROADCAST bitin DHCP 66 flags-field 122 is set to one, CMTS 12 sends the DHCPOFFERmessage to a broadcast IP 54 address (e.g., 255.255.255.255), instead ofthe address specified in DHCP 66 yiaddr-field 126. CMTS 12 does notupdate its ARP or other routing tables based upon the broadcast DCHP 66yiaddr-field 126 DHCP 66 chaddr-field 132 address pair.

Returning to FIG. 15B, CM 16 receives the one or more DHCPOFFER messagesand forwards them to CPE 18 at step 286. CM 16 uses the MAC 44 addressspecified determined by DHCP 66 chaddr-field 132 look-up in its routingtables to find the address of CPE 18 even if the BROADCAST bit in DHCP66 flags-field 122 is set. At step 290, CPE 18 receives the one or moreDHCPOFFER messages from CM 16. At step 292, CPE 18 selects one of theDHCPOFFER messages to allow a virtual connection to be establishedbetween data network 28 and CPE 18. Method 266 accomplishes addressingnetwork interface hosts from CPE 18 in data-over-cable system 10 withoutextensions to the existing DHCP protocol.

FIGS. 16A and 16B are a flow diagram illustrating a method 294 forresolving network host interfaces from CPE 18. At step 296, CPE 18receives the one or more DHCPOFFER messages from one or more DHCP 66servers associated with one or more network host interface available onCMTS 12. At step 298, CPE 18 chooses one offer of services from aselected network host interface. At step 300, CPE 18 generates aDHCPREQUEST message with the fields set as illustrated in Table 8 abovewith addresses for CPE 18 instead of CM 16. However, more or fewerfields could also be set. At step 302, CPE 18 sends the DHCPREQUESTmessage to CM 16. At step 304, CM 16 forwards the message to TRAC 24 viaPSTN 22.

At step 306, a DHCP 66 layer on TRAC 24 broadcasts the DHCPREQUESTmessage on its local network leaving DHCP 66 giaddr-field 130 intactsince it already contains a non-zero value. TRAC's 24 local networkincludes connections to one or more DHCP 66 proxies. The DHCP 66 proxiesaccept DHCP 66 messages originally from CPE 18 destined for DHCP 66servers associated with network host interfaces available on CMTS 12. Inanother embodiment of the present invention, TRAC 24 provides the DHCP66 proxy functionality, and no separate DHCP 66 proxies are used.

One or more DHCP 66 proxies on TRAC's 24 local network recognize theDHCPOFFER message and forward it to one or more of the DHCP 66 serversassociated with network host interfaces (e.g., IP 54 interfaces)available on CMTS 12 at step 308 in FIG. 16B. Since DHCP 66 giaddr-field130 in the DHCPDISCOVER message sent by CPE 18 is already non-zero, theDHCP 66 proxies leave DHCP 66 giaddr-field 130 intact.

One or more DHCP 66 servers for the selected network host interfaces(e.g., IP 54 interface) available on CMTS 12 receive the DHCPOFFERmessage at step 310. A selected DHCP 66 server recognizes a DHCP 66server identifier in DHCP 66 sname-field 134 or the IP 54 address thatwas sent in the DCHPOFFER message in the DHCP 66 yiaddr-field 126 fromthe DHCPREQUST message for the selected DHCP 66 server.

The selected DHCP 66 server associated with network host interfaceselected by CPE 18 in the DHCPREQUEST message creates and sends a DCHPacknowledgment message ("DHCPACK") to CMTS 12 at step 312 using the DHCP66 giaddr-field 130. The DHCPACK message is sent with the message fieldsset as illustrated in Table 9. However, other field settings can also beused. DHCP 66 yiaddr-field contains the IP 54 address for the selectednetwork host interface available on CMTS 12 for receiving data packetsfrom data network 28 for CPE 18.

At step 314, CMTS 12 receives the DHCPACK message. CMTS 12 examines theDHCP 66 giaddr-field 130 and looks up that IP address in its ARP tablefor an associated MAC 44 address. This is a MAC 44 address for CM 16,which sent the DHCPREQUEST message from CPE 18. CMTS 12 uses the MAC 44address associated with the DHCP 66 giaddr-field 130 and the DHCP 66yiaddr-field 126 to update its routing and ARP tables reflecting thisaddress pairing at step 316. At step 318, CMTS 12 sends the DHCPACKmessage on a downstream channel on cable network 14 to the IP 54 and MAC44 addresses, respectively (i.e., to CM 16). If the BROADCAST bit in theDHCP 66 flags-field 122 is set to one, CMTS 12 sends the DHCPACK messageto a broadcast IP 54 address (e.g., 255.255.255.255), instead of theaddress specified in the DHCP 66 yiaddr-field 126. CMTS 12 uses the MAC44 address associated with the DHCP 66 chaddr-field 130 even if theBROADCAST bit is set.

CM 16 receives the DHCPACK message. It examines the DHCP 66 yiaddr-field126 and chaddr-field 132, and updates its routing table and an ARProuting table to reflect the address pairing at step 320. At step 322,CM 16 sends the DHCPACK message to CPE 18 via CMCI 20 at IP 54 and MAC44 addresses respectively from its routing tables. If the BROADCAST bitin the DHCP 66 flags-field 122 is set to one, CM 16 sends the downstreampacket to a broadcast IP 54 address (e.g., 255.255.255.255), instead ofthe address specified in DHCP 66 yiaddr-field 126. CM 16 uses the MAC 44address specified in DHCP 66 chaddr-field 132 even if the BROADCAST bitis set to located CPE 18. At step 324, CPE 18 receives the DHCPACK fromCM 16 and has established a virtual connection to data network 28.

In the event that CPE 18 is not compatible with the configurationreceived in the DHCPACK message, CPE 18 may generate a DHCP 66 decline("DHCPDECLINE") message and send it to CM 16. CM 16 will transmit theDHCPDECLINE message up the PPP 50 link via PSTN 22 to TRAC 24. On seeinga DHCPDECLINE message TRAC 24 sends a unicast copy of the message toCMTS 12. CM 16 and CMTS 12 examine the DHCP 66 yiaddr-field 126 andgiaddr-field 130, and update their routing and ARP tables to flush anyinvalid pairings.

Upon completion of methods 266 and 292, CM 16 CMTS 12 have valid IP/MACaddress pairings in their routing and ARP tables. These tables store thesame set of IP 54 addresses, but does not associate them with the sameMAC 44 addresses. This is because CMTS 12 resolves all CPE 18 IP 54addresses to the MAC 44 address of a corresponding CM 16. The CMs 16, onother hand, are able to address the respective MAC 44 addresses of theirCPEs 18. This also allows DHCP 66 clients associated with CPE 18 tofunction normally since the addressing that is done in CM 16 and CMTS 12is transparent to CPE 18 hosts.

FIG. 17 is a block diagram illustrating a message flow 326 for methods268 and 294 in FIGS. 15A, 15B, and 16A and 16B. Message flow 326illustrates a message flow for methods 268 and 294, for adata-over-cable system with and without telephony return. In anotherembodiment of the present invention, CM 16 forwards requests from CPE 18via an upstream connection on cable network 14 to DHCP servers 160associated with one or more network host interfaces available on CMTS12.

Method 268 and 294 accomplishes resolving addresses for networkinterface hosts from customer premise equipment in a data-over-cablewith or without telephony return without extensions to the existing DHCPprotocol. Methods 268 and 294 of the present invention are used indata-over-cable system 10 with telephony return. However, the presentinvention is not limited to data-over-cable system 10 with telephonyreturn and can be used in data-over-cable system 10 without telephonyreturn by using an upstream cable channel instead of an upstreamtelephony channel.

Management of network services on a data network in a data-over-cablesystem

FIG. 18 is a block diagram illustrating a cable modem system withtelephony return 328. Cable modem system with telephony return 328 fromFIG. 18 is similar to the cable modem system with telephony return ofFIG. 1 except CM 16 has both and upstream and a downstream telephonyconnection to/from TRAC 24 via PSTN 22.

FIG. 19 is a flow diagram illustrating a method 330 for managing networkservices on a network device. At step 332, a network device receives afirst message on a first downstream connection from a first network. Thefirst message includes a list of network services available to thenetwork device on a third network. At step 334, the list of servicesfrom the first message is stored on the network device. At step 336, thenetwork device sends a second message over an upstream connection to asecond network. The second message contains a request for one or morenetwork services offered by the third network. At step 338, the networkdevice receives a third message from the second network on a seconddownstream connection. The third message indicates a status of therequest for one or more network services offered by the third network.

In an illustrative embodiment of the present invention, the networkdevice is CM 16, the first message is TSI message 76 (FIG. 4) and thesecond and third messages are IP 54 messages. However, the invention isnot limited to CM 16, TSI message 76 and IP 54 messages and othernetwork devices and messages could also be used.

FIG. 20 is a flow diagram illustrating a method 340 for managing networkservices from a cable modem. At step 342, CM 16 receives a TSI message76 from CMTS 12 on a downstream cable connection via cable network 14. Alist of services available to CM 16 on data network 28 is included asTLV encoded-data 90. TSI 76 is transmitted as a MAC 44 managementmessage with a message type of MAC management type value of TRI₋₋ TSI.However, other first messages or message types can also be used.

In an illustrative embodiment of the present invention, the list ofavailable services included as TLV encoded-data 90 is a small list ofservices or sites (e.g., network addresses) available to CM 16 on datanetwork 28. The list of available services may contain only a list of asmall number of Internet or intranet sites and services CM 16 is allowedto access. For example, CM 16 may be only allowed to access anelectronic kiosk HTML document on a company intranet and no otherservice or site. TLV encoded-data 90 in TSI message 76 would contain thesingle IP 54 address on the company intranet.

Returning to FIG. 20, at step 344 CM 16 stores the list of services fromTSI message 76 in an internal table. At step 346, CM 16 sends a first IP54 message in a PPP 50 datagram to TRAC 24 as via PSTN 22 over anupstream telephony connection. TRAC 24 forwards the first IP 54 messageto data network 28 via TRAC-NSI 30. TRAC 24 receives a second IP 54message from data network 28 in response to the first IP 54 message viaTRAC-NSI 30. In one embodiment of the present invention, the second IP54 message is sent only to TRAC 24 by data network 28, thereby keepingCMTS 12 and cable network 14 secure from requests for services on datanetwork 28 by CM 16. In another embodiment of the present invention, theIP 54 message is sent to both TRAC 24 and CMTS 12 by data network 28with TRAC 24 supplying an additional IP 54 address for CMTS 12 when thefirst IP 54 message is forwarded to data network 28. In an illustrativeembodiment of the present invention, only TRAC 24 forwards the second IP54 message to CM 16 indicating a status of CM's 16 request for serviceson data network 28.

Returning again to FIG. 20, at step 348 CM 16 receives the second IP 54message from TRAC 24 via PSTN 22 on a downstream telephony connection.CM 16 uses a two-way telephony pathway through TRAC 24 via PSTN 22 torequest services and receive responses from data network 28. In oneembodiment of the present invention, CM 16 does not receive responsemessages from CMTS 12 via cable network 14. As a result, requests fromnetwork services are made from CM 16 on lower bandwidth telephonyconnections instead of using high bandwidth cable connections foradministrative tasks and TRAC 24 provides an additional securitymechanism as is explained below. In another embodiment of the presentinvention, CM 16 receives response messages from TRAC 24 via PSTN 22 orCMTS 12 via cable network 14.

FIG. 21 is a flow diagram illustrating a method 350 for managing networkservices from a computer network. At step 352, a first message isreceived on a second network from a first network including a list ofservices available to a network device on a third network. At step 354,the list of services from the first message are stored in an internaltable on the second network. At step 356, a second message is receivedon a second network on an upstream connection from the network device.The second message contains a request for one or more network serviceson the third network.

At step 358, a test is conducted on the second network to determinewhether the network device is allowed to use the one or more servicesrequested in the second message using the list of services stored in theinternal table. If so, at step 360 the second message is forwarded tothe third network. At step 362, the second network receives a thirdmessage from the third network. The third message is a response for theone or more services requested in the first message. At step 364, thesecond network forwards the third message to the network device over asecond downstream connection. If the network device is requesting one ormore services on the third network that are not available to the networkdevice (i.e., not in the list of services), the first network sends afourth message back to the network device indicating a rejection to therequest for one or more services on the third network at step 366.Method 350 prevents the network device from using any services notindicated in the first message sent to the second network.

FIG. 22 is a flow diagram illustrating a method 366 for managing networkservices from a telephony remote termination system. At step 368, TRAC24 receives a MAC 44 message from CMTS 12 including a list of servicesavailable to CM 16 on data network 28. The list of services is stored inan internal table on TRAC 24 at step 370. At step 372, TRAC 24 receivesa first IP 54 message from CM 16 via PSTN 22 as a PPP 50 datagram overan upstream telephony connection. At step 374, if CM 16 requests one ormore services in the list maintained by TRAC 24 in the internal table,the first IP 54 message containing the request for one or more networkservices is forwarded to data network 28 at step 376.

At step 378, TRAC 24 receives a second IP 54 message from data network28 in response to the first IP 54 message sent by CM 16 at step 372. Inan illustrative embodiment of the present invention, the second IP 44message is received on TRAC 24 from data network 28 and not on CMTS 12,which normally receives data packets from data network for the cablemodem. In another embodiment of the present invention, the second IP 54message is received on both TRAC 24 and CMTS 12, but is forwarded to CM16 only from TRAC 24. In such an embodiment, TRAC 24 supplies datanetwork 28 with an IP 54 address for both TRAC 24 and CMTS 12. In yetanother embodiment of the present invention, the second IP 54 message isreceived on both TRAC 24 and CMTS 12 and is forwarded to CM 16 only overa downstream cable connection via cable network 14.

Returning to FIG. 22, the second IP 54 message is forwarded by TRAC 24to CM 16 via PSTN 22 over a downstream telephony connection at step 380.If CM 16 is requesting one or more services on data network 28 that arenot available to CM 16 at step 374, TRAC 24 sends a third IP 54 messageback to CM 16 indicating a rejection to the request for one or moreservices on data network 28 at step 382. Thus, TRAC 24 provides anadditional security mechanism to protect data-over-cable system 328.

The present invention is not limited to the messages and componentsdescribed for an illustrative embodiment and other messages andcomponents may also be used. An illustrative embodiment of the presentinvention allows a cable modem to request one or more sites or servicesavailable on a data network such as the Internet or an intranet by usinga telephony return pathway in the data-over-cable system. However, thepresent invention may also be used in a data-over-cable system withouttelephony return using a two-way cable connection, additional MAC 44management messages, and security checks from method 350 in CMTS 12instead of TRAC 24.

An illustrative embodiment of the present invention allows a cable modemto request one or more sites or services available on a data networksuch as the Internet or an intranet by using a telephony return pathwayin the data-over-cable system. A cable modem termination system and atelephony remote access concentrator cooperate to restrict services acable modem can subscribe to. Using a telephony return path improves thesecurity of the cable television system. In addition, the telephonyreturn path is used to provide administrative support on lower bandwidthconnections for a data-over-cable system by providing an administrativepathway outside of the higher bandwidth cable television connections.

It should be understood that the programs, processes, methods, systemsand apparatus described herein are not related or limited to anyparticular type of computer apparatus (hardware or software), unlessindicated otherwise. Various types of general purpose or specializedcomputer apparatus may be used with or perform operations in accordancewith the teachings described herein.

In view of the wide variety of embodiments to which the principles ofthe invention can be applied, it should be understood that theillustrated embodiments are exemplary only, and should not be taken aslimiting the scope of the present invention. For example, the steps ofthe flow diagrams may be taken in sequences other than those described,and more or fewer elements or component may be used in the blockdiagrams.

The claims should not be read as limited to the described order orelements unless stated to that effect. In addition, use of the term"means" in any claim is intended to invoke 35 U.S.C. §112, paragraph 6,and any claim without the word "means" is not so intended. Therefore,all embodiments that come within the scope and spirit of the followingclaims and equivalents thereto are claimed as the invention.

We claim:
 1. In a data-over-cable system including a network deviceconnected to a first network with a first downstream connection of afirst connection type, connected to a second network with an upstreamconnection of a second connection type and connected to the secondnetwork with a second downstream connection of a second connection type,the first network and second network connected to a third network withthe third connection type, a method of managing network services, themethod comprising the following steps:receiving a first message from thefirst network on the first downstream connection on the network device,wherein the first message includes a list of services on the thirdnetwork available to the network device; storing the list of servicesfrom the first message on the network device; sending a second messagefrom the network device on the upstream connection to the second networkrequesting one or more of the available network services on the thirdnetwork from the list of services from the first message; and receivinga third message on the second downstream connection from the secondnetwork on the network device indicating a status for one or moreavailable network services requested by the network device in the secondmessage.
 2. A computer readable medium having stored thereininstructions for causing a central processing unit to execute the stepsof the method of claim
 1. 3. The method of claim 1 wherein the firstnetwork is a cable television network, the second network is a publicswitched telephone network and the third network is a data network. 4.The method of claim 3 wherein the data network is any of the Internet orintranet.
 5. The method of claim 1 wherein the first connection type isa cable television connection, the second connection type is a telephonyconnection and the third connection type is an Internet Protocolconnection.
 6. The method of claim 1 wherein the first message ismanagement message for the network device including a list of networkaddresses for services available on the third network.
 7. The method ofclaim 1 wherein the first message is a medium access control message,the second and third messages are an Internet Protocol messages.
 8. Themethod of claim 1 wherein the network device is a cable modem.
 9. Themethod of claim 1 wherein the first message contains a list of less thanall of the services available on the third network.
 10. The method ofclaim 1 further comprising:receiving a third message from the thirdnetwork on the first network and the second network in response to thesecond message sent by the network device; and forwarding the thirdmessage to the network device only from the second downstream connectionon the second network.
 11. In a data-over-cable system including anetwork device connected to a first network with a first downstreamconnection of a first connection type, the network device connected to asecond network with an upstream connection of a second connection typeand connected to the second network with a second downstream connectionof a second network type, the first network and second network connectedto a third network with the third connection type, a method of managingnetwork services, the method comprising the following steps:receiving afirst message from the first network on the second network including alist of services on the third network available to the network device;storing the list of services available to the network device on thefirst network; receiving a second message from the network device on thesecond network on the upstream connection, wherein the second message isa request for one or more services available on the third network;determining whether the network device is allowed to request the more ormore services in the second message available on the third network usingthe list of services, and if so, forwarding the second message to thethird network; receiving a third message on the second networkindicating a status for the one or more services requested by thenetwork device in the second message; and forwarding the third messagefrom the second network over the second downstream connection to thenetwork device.
 12. A computer readable medium having stored thereininstructions for causing a central processing unit to execute the stepsof the method of claim
 11. 13. The method of claim 11 furthercomprising:determining whether the network device is allowed to requestthe one or more services available from the second message on the thirdnetwork, and if not, sending a fourth message over the second downstreamconnection to the network device, wherein the fourth message is arejection message for one or more of the services available on the thirdnetwork.
 14. The method of claim 11 further comprising:receiving a thirdmessage on the first network and on the second network, wherein thethird message indicates a status for the one or more services requestedby the network device in the second message; and forwarding the thirdmessage only over the second downstream connection from the secondnetwork to the network device.
 15. In a data-over-cable system includinga cable modem connected to a cable television network with a downstreamcable connection, the cable modem connected to a public switchedtelephone network with an upstream telephony connection and connected tothe public switched telephone network with a downstream telephonyconnection, the cable television network and public switched telephonenetwork connected to a data network, a method of managing networkservices, the method comprising the following steps:receiving a firstmessage from the cable television network on the downstream cableconnection on the cable modem, wherein the first message includes a listof services on the data network available to the cable modem; sending asecond message from the cable modem on the upstream telephony connectionto the public switched telephone network, wherein the second messageincludes a request for one or more of the available network services onthe data network from the list of services from the first message;forwarding the second message from the public switched telephone networkto the data network; receiving a third message on the public switchedtelephone network, wherein the third message indicates a status for theone or more services requested by the cable modem in the second message;and forwarding the third message from the public switched telephonenetwork over the downstream telephony connection to the cable modem. 16.A computer readable medium having stored therein instructions forcausing a central processing unit to execute the steps of the method ofclaim
 15. 17. The method of claim 15 further comprising:determiningwhether the cable modem is allowed to request the one or more servicesavailable on the data network, and if not, sending a fourth message overthe downstream telephony connection to the cable modem, wherein thefourth message is a rejection message for one or more of the servicesavailable on the data network.
 18. The method of claim 15 wherein thestep of receiving a first message from the cable television network onthe downstream cable connection on the cable modem includes receiving afirst message from a cable modem termination system connected to thecable television network.
 19. The method of clam 15 wherein the step ofsending a second message from the cable modem on the upstream telephonyconnection to the public switched telephone network includes sending asecond message from the cable modem on the upstream telephony connectionto a telephony remote access concentrator connected to the publicswitched telephone network.
 20. The method of claim 15 wherein the stepof receiving a third message on the public switched telephone networkincludes receiving third message on a telephony remote accessconcentrator connected to the public switched telephone network.
 21. Themethod of claim 15 wherein the step of receiving a third message on thepublic switched telephone network includes also receiving the thirdmessage on the cable television network.
 22. The method of claim 15further comprising:forwarding the third message from the cable modemtermination system over the downstream cable connection to the cablemodem.
 23. In a data-over-cable system including a cable modem connectedto a cable modem termination system on a cable television network andconnected to a telephony remote access concentrator on a public switchedtelephone network, the cable television network and public switchedtelephone network connected to a data network, a method of managingnetwork services, the method comprising the following steps:receiving afirst message on the telephony remote access concentrator from the cablemodem termination system, wherein the first message includes a list ofservices on the data network available to the cable modem; sending asecond message from the cable modem termination system to the cablemodem on a downstream cable connection, wherein the second messageincludes a list of services on the data network available to the cablemodem; receiving a third message on the telephony remote accessconcentrator from the cable modem on an upstream telephony connectionrequesting one or more services on the data network; determining on thetelephony remote access concentrator with the list of services from thefirst message whether the cable modem is allowed to request the one ormore services on the data network, and if so, forwarding the thirdmessage to the data network from the telephony remote accessconcentrator for the cable modem; and forwarding responses from the datanetwork from the telephony remote access concentrator to the cable modemon a downstream telephony connection via the public switched telephonenetwork, thereby allowing the cable modem to request one or moreservices on the data network without sending request messages orreceiving responses through the cable modem termination system on thecable television network.
 24. A computer readable medium having storedtherein instructions for causing a central processing unit to executethe steps of the method of claim 23.